Carbon Canisters are commonly used in the automotive industry to control the emission of hydrocarbons. For automobiles, hydrocarbon emissions may be produced during the filling of the fuel tank and during vehicle operation. When the engine is off, evaporation from the vehicle fuel system may occur.
Allowable hydrocarbon emission limits are set by government regulations. For example, the Low Emitting Vehicle-II (LEV-II) standard allows a certain amount of hydrocarbon emissions for a specific range of gross vehicle weight.
Carbon canisters may be part of an evaporative emission control system, which may include the fuel tank, vent and purge valves, and fuel lines. The carbon canister stores the fuel vapor generated in the system instead of having it escape into the atmosphere. The hydrocarbons are then burned off by purging the canister into the intake manifold when the engine is running.